ladybird/Libraries/LibWeb/CSS/Invalidation/LanguageInvalidator.cpp

/*
 * Copyright (c) 2026-present, the Ladybird developers
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibWeb/CSS/Invalidation/LanguageInvalidator.h>
#include <LibWeb/CSS/StyleScope.h>
#include <LibWeb/DOM/CharacterData.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/DOM/ShadowRoot.h>
#include <LibWeb/TraversalDecision.h>

namespace Web::CSS::Invalidation {

static void invalidate_descendants_affected_by_language_or_directionality(DOM::Element& element, bool is_directionality_change)
{
    // dir and lang both inherit, so all descendants' :dir() / :lang() matches and direction-dependent layout/text
    // need to be recomputed.
    element.for_each_shadow_including_inclusive_descendant([is_directionality_change](auto& node) {
        if (auto* element = as_if<DOM::Element>(node)) {
            if (!is_directionality_change)
                element->invalidate_lang_value();
            element->set_needs_style_update(true);
        }
        return TraversalDecision::Continue;
    });

    // :has(:dir(...)) and :has(:lang(...)) on ancestors aren't keyed on any property the regular invalidation
    // plan tracks, so explicitly schedule the :has() ancestor walk here.
    element.for_each_style_scope_which_may_observe_the_node([&](CSS::StyleScope& scope) {
        auto pseudo_class = is_directionality_change ? CSS::PseudoClass::Dir : CSS::PseudoClass::Lang;
        Vector<CSS::InvalidationSet::Property> properties {
            { CSS::InvalidationSet::Property::Type::PseudoClass, pseudo_class },
        };
        scope.record_pending_has_invalidation_mutation_features(element, properties);
        scope.schedule_ancestors_style_invalidation_due_to_presence_of_has(element);
    });
}

void invalidate_style_after_language_change(DOM::Element& element)
{
    invalidate_descendants_affected_by_language_or_directionality(element, false);
}

void invalidate_style_after_directionality_change(DOM::Element& element)
{
    invalidate_descendants_affected_by_language_or_directionality(element, true);
}

void invalidate_style_after_text_directionality_change(DOM::CharacterData& character_data)
{
    // dir=auto resolves an element's effective directionality from its text content, so any ancestor with dir=auto
    // can flip its :dir() match when this text changes. Recompute style on each such ancestor's subtree and propagate
    // :has(:dir(...)) invalidation up its ancestor chain.
    for (auto ancestor = character_data.parent_element(); ancestor; ancestor = ancestor->parent_element()) {
        if (ancestor->dir() != DOM::Element::Dir::Auto)
            continue;
        Vector<CSS::InvalidationSet::Property> properties {
            { CSS::InvalidationSet::Property::Type::PseudoClass, CSS::PseudoClass::Dir },
            { CSS::InvalidationSet::Property::Type::PseudoClass, CSS::PseudoClass::Empty },
        };
        ancestor->for_each_style_scope_which_may_observe_the_node([&](CSS::StyleScope& scope) {
            scope.record_pending_has_invalidation_mutation_features(*ancestor, properties);
        });
        invalidate_descendants_affected_by_language_or_directionality(*ancestor, true);
    }
}

}